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EC number: 209-967-5 | CAS number: 599-61-1
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Dissociation constant
Administrative data
Link to relevant study record(s)
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 24 August 2011 - 17 November 2011
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: This study has been performed according to an OECD guideline and in compliance with GLP principles.
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 112 (Dissociation Constants in Water)
- Version / remarks:
- (1981)
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 3.1
- Remarks on result:
- other: calculated value based on molecular structure; basic group: RC6H4NH3+.
- Remarks:
- Temperature is not specified.
- No.:
- #2
- pKa:
- 2.18
- Remarks on result:
- other: calculated value based on molecular structure; basic group: RC6H4NH3+.
- Remarks:
- Temperature is not specified.
- Conclusions:
- The pKa value for 3,3’-DDS could not to be determined using the spectrophotometric method. In view of the relatively low water solubility of the substance, the titration method was also considered to be not feasible to perform. Alternatively, the calculation method was used to estimate possible pKa values. In the logarithm range of 1 - 14 two pKa values for a basic group in the molecular structure of the test substance were calculated: 3.10 and 2.18.
Reference
Search for spectra of the pure molecule and the pure anion
Attempts were made to determine the pKavalues of the separable–NH2group in the test substance, thus a basic group.
The spectra recorded at pH 4 till pH 13 were comparable. The spectra recorded at pH 0, pH 1, pH 2 and pH 3 had different forms and are therefore called intermediate spectra. It was concluded that spectra recorded at pH>4 are of the non-ionized test substance, whereas spectra recorded at pH<4 are a combination of the ionized test substance and its non-ionized form.
Choice of an analytical wavelength
From comparing the spectra of the ionized substance with the spectra of the non-ionized substance, it was concluded that the difference in optical absorbance is maximal at 305 nm. Hence 305 nm was chosen as the analytical wavelength.
Only one wavelength could be selected though two pKa’s have to be determined which only differ by approximately 1 log unit. In principle, two specific wavelengths are required, one for each dissociation reaction. In order to test the applicability of the method, the study was continued.
Search for an approximate pKavalue
The optical absorbances at 305 nm were determined. As well as the actual pH values of the test solutions and actual pH values of the reference solutions. From these absorbances and the actual pH value, the approximate pKavalue was calculated. Actual pH values and optical absorbances at 305 nm.
actual pH values of the reference solutions |
actual pH values of the test solutions |
Absorbance for the test solution [units] |
pKavalue |
|
|
|
|
0.19 |
0.19 |
0 |
|
1.02 |
1.05 |
0.020 |
1.99 |
2.17 |
2.16 |
0.072 |
2.39 |
3.11 |
3.13 |
0.149 |
2.61 |
4.11 |
4.12 |
0.184 |
2.86 |
5.08 |
5.09 |
0.184 |
3.83 |
6.12 |
6.11 |
0.192 |
4.13 |
7.13 |
7.13 |
0.186 |
5.76 |
8.01 |
8.06 |
0.193 |
5.77 |
9.06 |
9.07 |
0.184 |
7.81 |
10.02 |
10.03 |
0.186 |
8.66 |
10.84 |
10.84 |
0.186 |
9.47 |
11.65 |
11.68 |
0.189 |
10.10 |
12.81 |
12.85 |
0.194 |
|
No approximate pKavalue could be calculated from above results because the pKavalues were not within ±0.1 log units as required. This is probably caused as the results were influenced by two pKa values which are close together. Since a specific wavelength was not found for each dissociation reaction, the spectrophotometric method cannot be used for the determination of the dissociation constants of 3,3’-DDS.
Due to the low water solubility of 3,3’-DDS, the titration method is also not feasible for this test substance. Therefore, the calculated pKavalues will be given as the final result.
Using the Perrin calculation method, the following pKavalues in the logarithm range of 1 - 14 for acidic and basic groups in the molecular structure of the test substance were calculated:
acidic: none
basic:
RC6H4NH3+ : pKa 3.10
RC6H4NH3+ : pKa 2.18
Description of key information
DETERMINATION OF PHYSICO-CHEMICAL PROPERTIES OF 3,3’-DDS, project 496966, 2011
Dr. Ir. E. Baltussen.
Study performed according to an OECD guideline 112 and in compliance with GLP principles.
Key value for chemical safety assessment
Additional information
In the logarithm range of 1 - 14 two pKa values for a basic group in the molecular structure of the 3,3'-DDS were calculated : 3.10 and 2.18.
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